I vaguely remember specifying "novt" as TTY on the command line, or things like "-novtswitch", "-keeptty" and similar stuff. But that's certainly dependent on the variant of X server in use. I also remember lots of patches floating around in various message boards that deal with patching out the TTY handling. After all, it's usually just a few lines within the sources that are easy to find (openvt, deallocvt, chvt are the tokens to search for).